in client.js function onSignalingMessage(notification, data) without tracks

[sword007]

in client.js

if (notification === 'stream') {
if (data.status === 'add') {
fireStreamAdded(data.data);
}
somtimes data.data without tracks eg.
{"id":"43b1bd13dfb44c74a5bc652ec5b79502","type":"forward","media":{"audio":{"status":"active","source":"mic","format":{"channelNum":2,"sampleRate":48000,"codec":"opus"},"optional":{"format":[{"sampleRate":16000,"codec":"isac"},{"sampleRate":32000,"codec":"isac"},{"channelNum":1,"sampleRate":16000,"codec":"g722"},{"codec":"pcma"},{"codec":"pcmu"},{"channelNum":2,"sampleRate":48000,"codec":"aac"},{"codec":"ac3"},{"codec":"nellymoser"},{"codec":"ilbc"}]}},"video":{"status":"active","source":"camera","original":[{"format":{"codec":"vp9"}}],"optional":{"format":[{"codec":"vp8"},{"profile":"CB","codec":"h264"},{"profile":"B","codec":"h264"}],"parameters":{"resolution":[{"width":480,"height":360},{"width":426,"height":320},{"width":320,"height":240},{"width":212,"height":160},{"width":160,"height":120},{"width":352,"height":288}],"bitrate":["x0.8","x0.6","x0.4","x0.2"],"framerate":[6,12,15,24],"keyFrameInterval":[100,30,5,2,1]}}}},"info":{"owner":"oY11_14ORZAScJWFAAAR","type":"webrtc","inViews":[]}}